Trace determinationof cyanide by derivatization and flame thermionic gas chromatography

Abstract A sensitive gas chromatographic method for the determination of cyanide at trace levels is described. The method is based on the derivatization of cyanide to benzonitrile, which is extracted with benzene and determined by flame thermionic gas chromatography. In the derivatization reaction, aqueous cyanide reacts with aniline and sodium nitrite in the presence of copper(II) sulphate and forms benzonitrile. Cyanide at concentrations between 3 ng/ml and 1.0 μg/ml can be detected with a linear response. Several anions tested do not interfere. The method was evaluated by analysing wastewater samples collected from various factories and by comparing the values obtained with those obtained by the pyridine-pyrazolone method, which has been used widely for the determination of cyanide. Good agreement was found between the two methods.